Why BMP files need converting
BMP is the bitmap format of Windows. In its common form it does not compress the picture at all: the run-length compression that BMP offers only works for images with 16 or 256 colors, not for full-color photos. That makes BMP easy for programs to read and write, but heavy to store and send.
| Photo size | Pixels | Full-color BMP file |
|---|---|---|
| 1920 × 1080 | 2.1 million | 5.9 MB |
| 3000 × 2000 | 6 million | 17.2 MB |
| 4000 × 3000 | 12 million | 34.3 MB |
3 bytes per pixel plus a small header. Sizes counted like this tool does, with 1 MB as 1,024 × 1,024 bytes.
A JPG of the same photo keeps what the eye sees and drops what it barely notices. At quality 90 the result looks the same, and the list below shows the exact size before and after for every file.
After converting
Still too large for a form with a size limit? The compress to target size tool gets a JPG under 100 KB, 200 KB or any limit you set. To make the picture smaller in pixels, use the image resizer, and to put several scans into one document, JPG to PDF.
Converting BMP to JPG
- 1Choose JPG for small files or PNG to keep every pixel.
- 2Drop your BMP files on the box. Each one converts as soon as it is added.
- 3Compare the sizes, then save the files one by one or as a ZIP.
Frequently asked questions
Why is my BMP file so big?
MDN notes that the simplest and most common kind of BMP is an uncompressed raster image. A full-color BMP stores 3 bytes for every pixel, so a 4000 × 3000 photo takes 36 million bytes, shown here as 34.3 MB. As JPG, the same photo is much smaller, and the list shows you the exact numbers.
JPG or PNG: which should I pick?
JPG, also called JPEG, for photos and scans you want to email or upload, because the file gets very small. PNG for screenshots, diagrams and pixel art, where you want every pixel exactly as it was. PNG is lossless, so it is larger than JPG but still much smaller than an uncompressed BMP.
What happens to transparency?
If your BMP has transparent parts, PNG keeps them, and JPG fills the transparent parts with the background color you choose, white by default.
Can I convert many BMP files at once?
Yes. Drop a whole folder worth of BMP files. They are converted one after another, and Download all puts every JPG in one ZIP file.
Are my files uploaded?
No. Your browser reads each bitmap and saves the new file on your device. Nothing is sent to a server.